Benchmark: JavaScript spread operator vs Object.assign performance with empty object as first argument

Tests:

Using the spread operator
const firstObject = { sampleData: 'Hello world' } const secondObject = { moreData: 'foo bar' } const finalObject = { ...firstObject, ...secondObject };
Using Object.assign
const firstObject = { sampleData: 'Hello world' } const secondObject = { moreData: 'foo bar' } const finalObject = Object.assign({}, firstObject, secondObject);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Using the spread operator
Using Object.assign

Fastest: N/A

Slowest: N/A

Latest run results:

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Autogenerated LLM Summary (model llama3.2:3b, generated one year ago):

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**Benchmark Explanation**

The provided JSON represents a JavaScript microbenchmark that compares the performance of two different approaches: using the spread operator (`...`) and `Object.assign` to merge two objects.

**Options Compared**

Two options are compared:

1. **Using the spread operator**: This approach uses the spread operator (`...`) to create a new object with the properties of the first object (`firstObject`) and then adds the properties of the second object (`secondObject`) using the spread operator again.
2. **Using `Object.assign`**: This approach uses the `Object.assign` method to merge two objects into one.

**Pros and Cons**

* **Using the Spread Operator:**
	+ Pros:
		- More readable and expressive syntax
		- Can be more intuitive for some developers
		- Works with arrays as well (e.g., `[...array, ...newArray]`)
	+ Cons:
		- May have performance overhead due to the creation of a new object
* **Using `Object.assign`:**
	+ Pros:
		- Faster and more efficient than using the spread operator
		- Has been around for longer and is widely supported
	+ Cons:
		- Less readable and expressive syntax (especially with multiple objects)
		- Can be less intuitive for some developers

**Library Used**

In this benchmark, `Object.assign` is used as a library to merge two objects.

**Special JS Features/Syntax**

None of the benchmark test cases use any special JavaScript features or syntax.

**Other Considerations**

When choosing between these approaches, consider the trade-off between performance and readability. If you prioritize speed and efficiency, using `Object.assign` might be a better choice. However, if you prefer a more expressive and readable syntax, using the spread operator could be a better fit.

Keep in mind that modern JavaScript engines have optimized both approaches to minimize overhead. The actual performance difference may be smaller than expected.

**Alternative Approaches**

There are other ways to merge objects in JavaScript, such as:

* Using the `merge` function from libraries like Lodash or Ramda
* Using a recursive function to concatenate objects
* Using a library like Immutables or Immutable.js for immutable data structures

However, these alternatives may introduce additional dependencies, complexity, or performance overhead.

I hope this explanation helps!

Related benchmarks:

JavaScript spread operator vs Object.assign performance with empty object as first argument (version: 0)

Comparing performance of: Using the spread operator vs Using Object.assign

Created: 2 years ago by: Guest

Jump to the latest result

Using the spread operator

Using Object.assign

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

No previous run results

Autogenerated LLM Summary (model llama3.2:3b, generated one year ago):